ICA-positive relatives (age 4-45 years) of individuals with Type I diabetes will undergo testing to determine their risk of developing Type I diabetes. Based on these results, ICA-positive individuals will be stratified into high risk (>50% chance of developing diabetes within 5 years) or moderate risk categories. Individuals in the high risk category will be offered participation in the third phase of this trial determine if interventions will prevent or delay the development of the diabetes. This third portion of the trial is described in a seperate proposal, "Diabetes Prevention Trial-Intervention/Parenteral".